MONTPELIER — A bill that would allow doctors to prescribe lethal doses of drugs to terminally ill patients takes its first step on a preordained path through the Senate when lawmakers host a public hearing in the chamber of the House this evening.

While no one can guarantee that the controversial legislation will win majority support in the Senate, advocates have been promised a vote on the body’s floor. And Senate leaders have charted in advance its course though the legislative process.

To proponents, the legislation will enable suffering patients to choose “death with dignity.” To its detractors, the bill establishes a dangerous precedent they say could diminish the value of human life.

“Most people feel very strongly about it one way or the other,” Sen. Claire Ayer, chairwoman of the Senate Committee on Health and Welfare, said Monday.

Ayer’s committee plays host to what promises to be an emotional night of testimony in Montpelier, where citizens will make cases for and against the bill. The event, which begins at 5 p.m. and will be broadcast live on Vermont Public Television, will be followed by committee hearings Wednesday and Thursday and a committee vote sometime Friday.

Ayer’s committee has the votes to pass the bill, which will then head to the Senate floor sometime next week. That’s where things could get interesting.

Ayer has agreed to postpone a vote on the floor, and instead refer the bill to the Senate Judiciary Committee, where one of its chief opponents, Sen. Dick Sears, will put the legislation through its paces. Sears, a Bennington County Democrat, said Monday that he has “dozens” of problems with the bill, ranging from the practical — like criminal liability for doctors — to the philosophical.

Adding to the intrigue is the fact that the bill has almost no chance of winning a favorable vote from Sears’ committee.

“I suspect it will be voted down in Judiciary 2-3,” Sears said.

As per an agreement with Ayer and Senate President John Campbell, however, Sears said he’s pledged in advance to an unconventional procedural move that would allow the legislation nonetheless to move from his committee back to the Senate floor.

“Because that was the deal that John Campbell made with the caucus,” Sears said. “It was pretty clear at (the Democratic) caucus in December that there was an agreement on this bill and several other controversial pieces of legislation that don’t have support in their committees of jurisdiction, that they would come out of committee anyway and be voted on by the body.”

Sears said he’ll stand by his pledge but that he won’t be shy about pointing out what he believes are deep flaws in the legislation while it’s under his committee’s review.

As to the bill’s prospects on the Senate floor, Ayer said, “I believe it will pass.”

Ayer’s committee will hear from a number of officials from Oregon, including former Gov. Barbara Roberts, who helped put in place a 15-year-old law after which the Vermont bill has been modeled. Ayer, an Addison County Democrat, said the “death with dignity” bill has been introduced in each of the six terms she’s served in the Senate.

“What makes it even a better time for it this year is we have 15 years of experience in Oregon,” Ayer said. “They’ve got a lot of good data to show it’s working like it was intended to work.”

Should the bill pass through the Senate, it would move next to the House, where most observers believe it stands a better chance at passage than defeat. House Speaker Shap Smith and members of his leadership team support the legislation, as do the leaders of many of the committees through which the bill would first have to pass.